This is the continuation of the development of a computer based radome design tool. Measured electric field patterns for a AGM-88 High Speed Antiradiation Missile radome were used to validate the computer model. This computer model is based on a method of moments solution of the E-field integral equation for bodies of revolution.

Topics: Radome, Method of moments, HARM

Journal of Research of the National Institute of Standards and Technology

Topics: method of moments, agglomerates, coupled dipole method, light scattering

Gas flows in microfluidic devices suffer from non-equilibrium effects. To capture various non-equilibrium phenomena in the slip and early transition regime, the hydrodynamic system is extended from the Navier- Stokes-Fourier equations to the regularised 26 moment equations via Grad s moment method based on kinetic theory. It is shown in this lecture that the extended hydrodynamic equations can be effectively applied to micro-electro-mechanical-systems analytically and numerically. Well known...

Topics: DTIC Archive, DARESBURY LAB (UNITED KINGDOM), *GAS FLOW, HYDRODYNAMICS, METHOD OF MOMENTS,...

921
921

Jul 20, 2012
07/12

by
Golden Engineering

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AN-SOF is a software for the modeling and simulation of antenna systems and general radiating structures. Transmitting and receiving antennas can be modeled and several antenna parameters can be obtained (gain, efficiency, input impedance, VSWR, radiated and consumed powers, RCS, etc.). A complete view of the radiation and scattering properties of a structure can be obtained with a fully angle-resolved pattern. Colored mesh and surface for the clear visualization of radiation lobes are...

Topics: antenna modeling, antenna simulation, antenna design, antenna analysis, numerical electromagnetics,...

China's unbundling reform in 2002 aimed to introduce competitiveness into the power industry. With the increasing concern about the environmental issue and climate change, the ability to balance the reduction of carbon emissions with economic benefits may to a great extent determine the competitiveness of power generation sector. This study first adopts the game cross-efficiency approach to evaluate the environmental efficiencies of the generation sector in China's 30 provinces. The results...

Topics: China, Data envelopment analysis, Environmental efficiency, Game cross-efficiency, Generalized...

Small symmetric dual reflector antennas suffer from low efficiency due to subreflector blockage of the main reflector and subreflector scattering. These can be reduced by slicing the main dish and translating its rotational axis, along with modifying the subreflector geometry. This type of design is usually applied to low-frequency reflectors, but high-frequency analysis techniques are used. Consequently the agreement between measured and computed data is not as good as it would be for a...

Topics: Antennas, Reflector, Method of moments analysis of displaced-axis dual reflector antennas

158
158

May 29, 2011
05/11

by
Bolotin, Gary; Boyce, Le

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This paper will present several methods for adjusting clock skew variations that occur in a n accumulative z-axis interconnect system. In such a system, delay between modules in a function of their distance from one another. Clock distribution in a high-speed system, where clock skew must be kept to a minimum, becomes more challenging when module order is variable before design.

Topics: MATHEMATICAL MODELS, TURBULENCE, TURBULENT FLOW, METHOD OF MOMENTS, REYNOLDS STRESS, KOLMOGOROV...

75
75

Aug 1, 2010
08/10

by
Bogard, D. D.; Garrison, D. H

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The observation that the K-Ar, Pb-Pb, and Rb-Sr ages of a significant number of lunar highland rocks were reset in the interval of 4.1-3.8 Ga ago led to the concept of a cataclysmic bombardment of the moon during this period. An important consideration for understanding the early bombardment history of the solar system, including the moon, is whether evidence also exists in meteorites for resetting of radiometric ages by cataclysmic bombardment of their parent bodies. A comparison of...

Topics: APERTURES, FREQUENCIES, MATHEMATICAL MODELS, SELECTIVE SURFACES, SPECTRAL METHODS, METAL SHEETS,...

Topic modeling is a generalization of clustering that posits that observations (words in a document) are generated by multiple latent factors (topics), as opposed to just one. The increased representational power comes at the cost of a more challenging unsupervised learning problem for estimating the topic-word distributions when only words are observed, and the topics are hidden. This work provides a simple and efficient learning procedure that is guaranteed to recover the parameters for a...

Topics: DTIC Archive, CALIFORNIA UNIV IRVINE, *ALGORITHMS, ALLOCATIONS, CLUSTERING, METHOD OF MOMENTS

314
314

May 30, 2011
05/11

by
Papila, Nilay; Shyy, Wei; Griffin, Lisa W.; Dorney, Daniel J

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Turbine performance directly affects engine specific impulse, thrust-to-weight ratio, and cost in a rocket propulsion system. A global optimization framework combining the radial basis neural network (RBNN) and the polynomial-based response surface method (RSM) is constructed for shape optimization of a supersonic turbine. Based on the optimized preliminary design, shape optimization is performed for the first vane and blade of a 2-stage supersonic turbine, involving O(10) design variables. The...

Topics: APPROXIMATION, COMPUTATIONAL FLUID DYNAMICS, DISTRIBUTION MOMENTS, DERIVATION, METHOD OF MOMENTS,...

142
142

Jun 12, 2011
06/11

by
Lada, Charles J

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This grant funds a research program to use infrared extinction measurements to probe the detailed structure of dark molecular cloud cores and investigate the physical conditions which give rise to star and planet formation. The goals of this program are to acquire, reduce and analyze deep infrared and molecular-line observations of a carefully selected sample of nearby dark clouds in order to internal structure of starless cloud cores and to quantitatively investigate the evolution of such...

Topics: JP-8 JET FUEL, FIRES, RADIATIVE TRANSFER, COMBUSTION PHYSICS, GRAY GAS, MONTE CARLO METHOD, RAY...

The printed dipole antenna on thin polyimide film is calculated by using WIPL-D and IE3D based on the method of moment, Micro-Stripes based on TLM method. Its input impedance characteristics are compared with measured data and discussed.

Topics: DTIC Archive, Taguchi, Mitsuo, NAGASAKI UNIV (JAPAN), *NUMERICAL ANALYSIS, *DIPOLE ANTENNAS, THIN...

Coupling between two waveguide-fed planar slot arrays has been investigated using full-wave analysis. The analysis employs the method-of-moments solution to the pertinent coupled integral equations for the aperture electric field of all slots. In order to compute coupling between two arrays, the input port of the first array is excited with a TE(sub 10) mode wave while the second one is match-terminated. After solving the moment method matrix equations, the aperture fields of all slots are...

Topics: NASA Technical Reports Server (NTRS), WAVEGUIDES, ANTENNA DESIGN, ELECTRIC FIELDS, ANTENNA ARRAYS,...

170
170

Jun 12, 2011
06/11

by
Vedantam, Nanda Kishor

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The objective of this study was to investigate the effects of the mean flow profiles on the instability characteristics in the near-injector region of low-density gas jets injected into high-density ambient gas mediums. To achieve this, a linear temporal stability analysis and a spatio-temporal stability analysis of a low-density round gas jet injected vertically upwards into a high-density ambient gas were performed by assuming three different sets of mean velocity and density profiles. The...

Topics: ROBUSTNESS (MATHEMATICS), COMPUTATIONAL FLUID DYNAMICS, UNCERTAIN SYSTEMS, SENSITIVITY, DERIVATION,...

Many authors have warned of the hazards involved in fitting Pearson curves on the basis of empirically determined moments. For the problem of estimating a percentage point of a Pearson curve on the basis of empirical moment estimates, the delta method easily yields an approximation to the variability of the estimated quantile. This report describes a crude computer program for assisting quantitatively the size of these hazards in the case of Pearson Type IV curves (an important family including...

Topics: DTIC Archive, Johnstone,Iain, STANFORD UNIV CA DEPT OF STATISTICS, *COMPUTER PROGRAMS, *CURVE...

382
382

May 29, 2011
05/11

by
Schultz-Grunow, F

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Based upon a simplified representation of the mode of operation of the pulse-jet tube, the effect of the influences mentioned in the title were investigated and it will be shown that, for a jet tube with a form designed to be aerodynamically favorable, the ability to operate is at least questionable. This investigation will account for the important practical observation made by Paul Schmidt that the ratio of the effective valve cross-sectional area to the tube cross section may not be of any...

Topics: AERODYNAMIC COEFFICIENTS, LIFT, AEROELASTICITY, METHOD OF MOMENTS, UNSTEADY AERODYNAMICS, LAPLACE...

A numerical method is presented to determine electromagnetic shielding effectiveness of rectangular enclosure with apertures on its wall used for input and output connections, control panels, visual-access windows, ventilation panels, etc. Expressing EM fields in terms of cavity Green's function inside the enclosure and the free space Green's function outside the enclosure, integral equations with aperture tangential electric fields as unknown variables are obtained by enforcing the continuity...

Topics: NASA Technical Reports Server (NTRS), ELECTROMAGNETIC FIELDS, PENETRATION, ELECTROMAGNETIC...

Herein the electromagnetic scattering is determined using the Finite Element Method. In particular the radar cross section of the scatterer is estimated. Comparison between the Finite Element Method (FEM), Method of Moments (MoM) and the method of Physical Optics (PO) is made in one numerical example. In another numerical example, the convergence rate is compared using pure h-refinement, p-enrichment and with a priori hp-adaptive refinements. The gain using the hp-adaptive approach is...

Topics: DTIC Archive, Sehlstedt, N, SWEDISH DEFENCE RESEARCH AGENCY STOCKHOLM, *FINITE ELEMENT ANALYSIS,...

This article presents a numerical approximation scheme, based upon the method of moments, to evaluate moisture distributions within a composite plate from data on total moisture weight-gain. Although it is assumed that the diffusion process remains linear, the scheme applies to moisture uptake data which depart from classical predictions. Two examples are provided to demonstrate the validity of the scheme.

Topics: DTIC Archive, Weitsman, Y J, TENNESSEE UNIV KNOXVILLE DEPT OF ENGINEERING SCIENCE AND MECHANICS,...

Present trends in antenna development go toward the integration on the same antenna aperture of more functions operating in separate frequency bands. In view of this, the necessity to look at new Frequency Selective Surface (FSS) concepts becomes evident. These structures should have pass-bands corresponding to the antenna operational frequencies sandwiched between sharp stop-bands. An advanced tool has been developed at TNO for the analysis and design of multi-layer FSSs. In the frame of Phase...

Topics: DTIC Archive, Francavilla, A, TNO DEFENCE SECURITY AND SAFETY THE HAGUE (NETHERLANDS), *ANTENNA...

This paper presents a novel method for the element characterization of printed reflectarray antennas. Their characterization requires the calculation of the phase of the reflection coefficient versus the patch dimension (phase diagram), when the structure is illuminated by a uniform plane wave. The calculation of the phase diagram is based on the full-wave analysis of the structure in a limited number of points, and a polynomial interpolation of the phase, which takes advantage of a...

Topics: DTIC Archive, Bozzi, Maurizio, PAVIA UNIV (ITALY) DEPT OF ELECTRONICS, *MODELS, *PERTURBATION...

An analysis has been performed on the aerodynamics of the Cassini spacecraft as it passed through the atmosphere of Titan with and without the Huygens probe attached. The free stream density of Titan s atmosphere was measured by two methods. However, these methods resulted in very different values of density, one result being 3-5 times higher than the other. In an attempt to understand the source of this discrepancy and verify the assumptions made by and the original engineering analysis...

Topics: NASA Technical Reports Server (NTRS), AERODYNAMIC DRAG, CASSINI MISSION, HUYGENS PROBE, AERODYNAMIC...

This thesis project modeled a microstrip ring-hybrid dipole that is capable of simultaneously producing a sum pattern and difference pattern using the method of moments (MoM) based on the Rao-Wilton-Glisson (RWG) edge elements. The ring- hybrid dipole is simply a ring-hybrid coupler driving a dipole antenna. A two-feed point dipole model was developed and its antenna parameters were found to be a good representation of the ring-hybrid dipole actual values. In the feed network modeling, the...

Topics: DTIC Archive, Ong, Chee H, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *HYBRID SYSTEMS, *ANTENNA ARRAYS,...

A computer program is presented which employs the moment method representation of wire antennas in combination with the Uniform Theory of Diffraction to model antennas on a satellite body. The development of the program is not completely done in that multiple diffractions are not yet included. In some analysis situations this will be of no concern while in others it may be a limitation on the use of the program. (Author)

Topics: DTIC Archive, Doan,D L, OHIO STATE UNIV COLUMBUS ELECTROSCIENCE LAB, *COMPUTERIZED SIMULATION,...

Dirichlet mixed models find wide application and the estimation of these models is usually achieved through the method of moments. We present an iterative hybrid algorithm for obtaining the (MLE) maximum likelihood estimate employing both modified Newton-Raphson and E-M (electro-magnetics) methods. This successful MLE algorithm enables calculation of a jackknife MLE. Simulation comparison of the three estimates is provided. The MLE substantially improves upon the moments estimator particularly...

Topics: DTIC Archive, Leeds, Steve, STANFORD UNIV CA DEPT OF STATISTICS, *DIRICHLET INTEGRAL, *ESTIMATES,...

FEMOM3DS is a computer code written in FORTRAN 77 to compute electromagnetic(EM) scattering characteristics of a three dimensional object with complex materials using combined Finite Element Method (FEM)/Method of Moments (MoM) technique. This code uses the tetrahedral elements, with vector edge basis functions for FEM in the volume of the cavity and the triangular elements with the basis functions similar to that described for MoM at the outer boundary. By virtue of FEM, this code can handle...

Topics: NASA Technical Reports Server (NTRS), USER MANUALS (COMPUTER PROGRAMS), FORTRAN, ELECTROMAGNETIC...

A technique which combines the Method of Moments and the Geometrical Theory of Diffraction into a single Hybrid Technique is incorporated into a computer program for determining the performance of wire-type antennas on a planar satellite panel which is joined to other planar panels on each of its sides. The computer program, which is still undergoing revisions, is capable of handling up to five antennas on a single satellite metallic panel. (Author)

Topics: DTIC Archive, Thiele,G A, OHIO STATE UNIV COLUMBUS ELECTROSCIENCE LAB, *ARTIFICIAL SATELLITES,...

The method of moments is used to define and derive expressions for laser beam deflection and beam radius broadening for high-energy propagation through the Earth s atmosphere. These expressions are augmented with the integral invariants of the corresponding nonlinear parabolic equation that describes the electric field of high-energy laser beam to propagation to yield universal equations for the aforementioned quantities; the beam deflection is a linear function of the propagation distance...

Topics: NASA Technical Reports Server (NTRS), METHOD OF MOMENTS, WAVE PROPAGATION, HIGH POWER LASERS,...

Under the Department of Defense (DoD) Common High Performance Computing Software Support Initiative (CHSSI), the goal of this effort was to parallelize the electromagnetic modeling tool WIPL-D (Wires, Plates and Dielectrics). WIPL-D utilizes a Method of Moments technique to solve Maxwell's Equations. Three evaluation criteria were used to evaluate the effort: 1) accuracy of the code as compared to the commercial program WIPL-D; 2) scalability of the code when using multi-processor High...

Topics: DTIC Archive, Benincasa, Milissa, BLACK RIVER SYSTEMS COMPANY INC UTICA NY, *PARALLEL PROCESSING,...

Surface formulation of method of moments gives the best results in electromagnetic analysis when geometrical modeling is performed with quadrilateral patches. Quadrilateral modeling, however, can be very difficult. Many structures, e.g. different microwave devices, can be easily modeled using polygonal surfaces. This paper presents general method for conversion of polygonal model into quadrilateral model. Proposed method is illustrated on real microwave filter.

Topics: DTIC Archive, Tasic, Miodrag S, BELGRADE UNIV (YUGOSLAVIA) FACULTY OF ELECTRICAL ENGINEERING,...

The bistatic scattering from a bent wire chiral has been analyzed and a computer modeling capability has been developed. A simple model was also developed to aid in interpreting the chiral body's scattering. Behavior of the scattered fields was investigated as the chiral's geometry was varied. Data was presented that would be useful in the design of chiral media. Keywords: Scattering, Wire scatterer, Chiral, and Moment method.

Topics: DTIC Archive, Buck, Allan C, ROME AIR DEVELOPMENT CENTER GRIFFISS AFB NY, *ELECTRIC WIRE,...

A planar dipole grid antenna is described deposited on an active frequency selective (FSS) or polarization sensitive surface (PSS) electronically tuneable to control the spatial phase distribution and reflective/transmissive amplification. Such dipole grids can be used, for example, in reflector antenna systems composed of multiple reflective and/or transmissive subsystems to achieve and serve highly cost-effective multi-purpose applications. It is discussed how the resonant frequency or/and...

Topics: DTIC Archive, Edenhofer, P, BOCHUM UNIV (GERMANY F R), *FREQUENCY, *POLARIZATION, *DIPOLE ANTENNAS,...

An investigation of the merits of techniques that may result in a reduced version of an antenna modeling code applicable to small problems and small computer resources. The result is the identification of one promising numerical approach suggested by Dr DR Wilton of the University of Mississippi. The approach has been coded in BASIC and implemented on a microcomputer. The computer code has been dubbed MININEC (Mini-Numerical Electromagnetics Code). MININEC solves an integral equation relating...

Topics: DTIC Archive, Julian,Alfredo J, NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA, *ELECTRIC FIELDS,...

Matrix methods for solving integral equations via direct solve LU factorization are presently limited to weeks to months of very expensive supercomputer time for problems sizes of several hundred thousand unknowns. This report presents matrix LU factor solutions for electromagnetic scattering problems for problem sizes to one million unknowns with thousands of right hand sides that run in mere days on PC level hardware. This EM solution is accomplished by utilizing the numerical low rank nature...

Topics: NASA Technical Reports Server (NTRS), ELECTROMAGNETIC SCATTERING, MATRIX METHODS, COMPRESSING,...

A frequency selective surface (FSS) composed of apertures in a metallic sheet is known as the inductive FSS. The infinite inductive FSS theory is derived and the aperture fields are solved by a spectral domain formulation with method of moments solution. Both full domain and subsectional basis functions are studied. A locally planar technique (LPT) is used to determine the forward scattered field from a generally shaped inductive FSS with arbitrary illumination.

Topics: NASA Technical Reports Server (NTRS), APERTURES, FREQUENCIES, MATHEMATICAL MODELS, SELECTIVE...

The applicability of tractable first-order non-Gaussian models for the ambient noise probability distribution is investigated. The models considered here are the Gauss-Gauss mixture model and the Johnson S system of probability density functions. The moment generating function method is used to fit the sample data to the Gauss-Gauss mixture model while the method of quantile matching is used to fit the data to the Johnson probability density functions. The results show that the Johnson system...

Topics: DTIC Archive, Torrez, William C, NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA, *AMBIENT NOISE, METHOD OF...

The effect of dielectric substrate on the performance of infinite arrays of single-polarized Vivaldi antennas is studied by computing the input impedance of an antenna in an array environment using full wave method of moments techniques. It is found that dielectric permittivity plays an important role in the wideband performance of such arrays, and comparison with dielectric-free cases for similar geometries is also included to bring out the impact of the presence of the substrate. The effect...

Topics: DTIC Archive, Kasturi, S., Schaubert, D. H., MASSACHUSETTS UNIV AMHERST, *DIELECTRICS, *SLOT...

Every object has the ability to radiate and scatter electromagnetic waves. The ability to predict frequencies of maximum radiation or scattering has been limited to simple objects, such as dipoles, or objects with high degrees of symmetry. This thesis describes modifications that can be made to a computational electromagnetic technique, the Method of Moments, to allow for such. predictions to be made for complex metallic objects. This new technique has been implemented as a MATLAB computer...

Topics: DTIC Archive, Lintz, William A., NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *MAGNETIC RESONANCE,...

377
377

Jul 26, 2010
07/10

by
Schmeckpeper, K. R

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The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA first completed an analysis of the Electrical Power Distribution and Control (EPD and C) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to...

Topics: ANTENNA RADIATION PATTERNS, INTEGRAL EQUATIONS, LOSSY MEDIA, METHOD OF MOMENTS, DIFFRACTION, FLAT...

388
388

May 26, 2011
05/11

by
Shen, Hao; Tam, Christopher K. W

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An imperfectly expanded supersonic jet, invariably, radiates both broadband noise and discrete frequency sound called screech tones. Screech tones are known to be generated by a feedback loop driven by the large scale instability waves of the jet flow. Inside the jet plume is a quasi-periodic shock cell structure. The interaction of the instability waves and the shock cell structure, as the former propagates through the latter, is responsible for the generation of the tones. Presently, there...

Topics: FINITE ELEMENT METHOD, METHOD OF MOMENTS, DIFFERENTIAL EQUATIONS, FREQUENCY RESPONSE, FREQUENCY...

Important aerospace electromagnetics problems include the evaluation of antenna performance on aircraft and the prediction and control of the aircraft's electromagnetic signature. Due to the ever increasing complexity and expense of aircraft design, aerospace engineers have become increasingly dependent on computer solutions. Traditionally, computational electromagnetics (CEM) has relied primarily on four disparate techniques: the method of moments (MoM), the finite-difference time-domain...

Topics: NASA Technical Reports Server (NTRS), ANTENNA RADIATION PATTERNS, COMPUTER TECHNIQUES,...

Section 1 describes a technique estimating the amplitude and phase of guided waves excited on finite dielectric slabs by incident plane waves. The procedure is based on the moment method, but it extends that method by postulating an explicit form for the guided waves and solving for the guided wave amplitudes. The method solves for the two guided waves that travel in opposite directions parallel to the slab. Experiment verified the technique. Section 2 describes nearfield scattering by a...

Topics: DTIC Archive, Tricoles,G, GENERAL DYNAMICS SAN DIEGO CALIF ELECTRONICS DIV, *DIELECTRICS,...

The computation of electromagnetic scattering from a nanowire requires the solution of a system of linear equations of the form, Ax=b, where the dimension of the matrix A increases with the number of unknowns. Previously, we had implemented a bi-conjugate gradient algorithm to iteratively solve this system of equations. However, this method converges very slowly when the convergence criterion is made stringent. An improved version of the algorithm, namely stabilized bi-conjugate gradient...

Topics: DTIC Archive, Singh, Surendra, TULSA UNIV OK DEPT OF ELECTRICAL ENGINEERING, *SOLUTIONS(GENERAL),...

This project has involved both numerical simulation of electromagnetic scattering for ultra-wideband synthetic aperture radar (SAR) for foliage and ground penetrating radar (FOPEN and GPEN, respectively). We have developed a fast multipole method (FMM) model for electromagnetic scattering from electrically large conducting targets in the presence of a half space. With application to scattering from surface/subsurface unexploded ordnance (UXO), as well as for scattering from surface vehicles,...

Topics: DTIC Archive, Carin, Lawrence, DUKE UNIV DURHAM NC DEPT OF ELECTRICALAND COMPUTER ENGINEERING,...

A goal of the research project was to develop the modified diakoptic theory into an efficient method for analyzing and designing antenna structures and distributed parameter circuits. A second goal of the project was to develop the numerical methods needed to implement the analysis techniques. And final goal was to perform laboratory measurements whose date enable one to corroborate the accuracy of the theoretical/numerical methods of the modified diakoptic theory. The three goals have been...

Topics: DTIC Archive, Butler, Chalmers M, CLEMSON UNIV SC, *ANTENNAS, METHODOLOGY, DISTRIBUTION,...

The author develops estimates for the parameters of Dirichlet-multinomial distribution (DMD) when there is insufficient data to obtain maximum likelihood or method of moment estimates known in the literature. We do, however, have supplementary beta-binomial data pertaining to the marginals of the DMD, and use these data when estimating the DMD parameters. A real situation and data set are given where the estimates are applicable. Keywords: Asymptotic properties.

Topics: DTIC Archive, Danaher, Peter J, FLORIDA STATE UNIV TALLAHASSEE DEPT OF STATISTICS, *ESTIMATES,...

Basis functions were studied and identified that provide efficient and accurate solutions for the induced patch currents and the reflection phase in microstrip reflect arrays. The integral equation of an infinite array of microstrip elements in the form of patches or crossed dipoles excited by a uniform plane wave is solved by the method-of-moments. Efficient choices of entire domain basis functions that yield accurate results have been described.

Topics: NASA Technical Reports Server (NTRS), ANTENNA ARRAYS, MICROSTRIP ANTENNAS, REFLECTOR ANTENNAS,...

The design and analysis of a series-fed, low-loss, inverted microstrip array antenna, operating at 1.413 GHz is presented. The antenna is composed of two subarrays. Each subarray consists of an equal number of microstrip patches all connected together with microstrip lines. In the first design microstrip array for linear polarization is presented which incorporated a series feeding technique. The next design, which is capable of dual linear polarization (V-polarization and H-polarization),...

Topics: NASA Technical Reports Server (NTRS), ANTENNA RADIATION PATTERNS, DESIGN ANALYSIS, ANTENNA ARRAYS,...

143
143

May 31, 2011
05/11

by
OKeeffe, James; Mingo, Natalio; Han, Ji

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We conclude that the conducting mode pi is the most likely responsible for conduction in experimental mercury-nanotube contacts. The total conductance approaches a saturation value as the dipping length is increased. There are two distinct regimes, strong and weak coupling, characterized by saturation conductances of 0 or 1G(sub o). We have calculated the partial conductance at each nanotube unit cell. The partial conductance exhibits oscillations due to reflection at the end of the tube.

Topics: COMPUTATIONAL FLUID DYNAMICS, UNCERTAIN SYSTEMS, CONVECTION-DIFFUSION EQUATION, TWO DIMENSIONAL...

Defining the electromagnetic environment inside a graphite composite fairing due to lightning is of interest to spacecraft developers. This paper is the first in a two part series and studies the shielding effectiveness of a graphite composite model fairing using derived equivalent properties. A frequency domain Method of Moments (MoM) model is developed and comparisons are made with shielding test results obtained using a vehicle-like composite fairing. The comparison results show that the...

Topics: NASA Technical Reports Server (NTRS), LIGHTNING, COMPOSITE STRUCTURES, FAIRINGS, MATHEMATICAL...